A whore's "pet name" for a boyfriend. The reasoning behind it is because "bubby" is another name for binky and if a female is calling a male there "binky" there is only one part in a male's body that will go in their mouth just to shut them up. That's right his penis.

Bubby is a name of a hilljack living in a trailer in the backwoods, possibly in West Virginia. What inbreds call their brothers or sons. Bubby's have rotted out yuck teeth, kinda resembling "meth mouth", dragon breath that makes a bystander's eyebrows fall out, extremely funky B.O. that makes his clothing stand up when he eventually takes them off and last but not least massive toe fungus with gnarly toenails to boot.

Hey, Paw tell Bubby to come in from shooting dem der 'hogs and eat his grits.
Bubby and sissy are setting to make a 'lil varmit here soon.